A total number of (78) subjects were examined in this study. All subjects were selected from the Outpatient clinic of otorhinolaryngology department, Minia university hospital ( tertiary referral hospital), from June 2015 to April 2016.
The type of study design is a case-control study. Obese children are included in the experimental group, while the control group includes average-weight children. their age range from 6 to 17 years. The control group (group-A) consisted of 20 children, eight boys, and twelve girls, while the experimental group (group-B) consisted of 58 children, 26 boys, and 32 girls.
The main inclusion criteria of the control group is the average body weight. In contrast, the experimental group comprises obese children with a body mass index (BMI) of more than 95th percentile according to the Center for Disease Control and Prevention (CDC) criteria for obese children. The other inclusion criteria are that both groups have no history of systemic disease as hypertension or hyperlipidemia, affecting the hearing. Also, there is no history of hearing loss or delayed language development and no positive consanguinity between parents.
The exclusion criteria in both groups are a history of associated systemic disease that could affect the hearing as hypertension, hyperlipidemia, autoimmune diseases, or congenital anomalies. Children with a history of consanguinity were also excluded.
The only difference between both groups is BMI as obese children have BMI more than 95th percentile while the other control group has an average weight according to CDC criteria.
Parents of the participated children had been informed about the aim of the study and its detailed procedures. We obtained informed written consent from the parents/ guardian of the participating children, and the research ethics committee of the Faculty of Medicine, Minia University, approved the current study. all methods used agrees with Helsinki accord.
All children who participated in the current study were subjected to full history taking, including prenatal, perinatal, neonatal, postnatal, developmental, and family history. Both groups were subjected to general medical examination that done by pediatrician; then, otorhinolaryngological evaluation including Otologic examination were done. Tympanometry, and acoustic reflex testing were performed, according to the child's age and reliability, either conditioned play audiometry for younger children with an age range from 3 to 10 years and conventional audiometry for older children above the age of 10 years, both audiometries have the same results regarding pure tone results. Audiometry was performed using audiometer Madsen Astera and sound-treated room amplisilence. Air conduction threshold was measured at frequencies 0.25, 0.5, 1, 2, 4, 8 kHz. Bone conduction threshold was measured in frequencies 0.5, 1, 2, and 4 kHz.
The examination includes determining the hearing threshold for extended high-frequency audiometry in the frequency range (9, 10, 11,200, 12, 500, 14, 18, 20 kHz). Laboratory investigations include; Complete blood picture (CBC), lipid profile, blood sugar, renal and liver function tests to exclude any underlying systemic diseases.
BMI is calculated according to birth date, date of measurement, Sex, height, and weight. (Centers for Disease Control and Prevention), www.cdc.gov/healthyweight/assessing/bmi/index.html). Before measuring the height and weight, the children were asked to remove outer clothing (e.g., coats), shoes, and removable hair accessories and remove personal items from their pockets. The height was measured to the nearest inch using a weighted measuring tape attached to the wall. Children placed their backs and heels against the wall, then a measuring triangle was placed on the children's heads to form a right angle with the wall. The height measurement was taken from the lower edge of the triangle. The weight was also measured to the nearest gram using an electronic scale placed on an uncarpeted floor. The scale was zero balanced before each child was weighted.
Measurement of transient evoked otoacoustic emission (TEOAE) using Smart Intelligent hearing system (IHS), Stimuli were 75us rectangular clicks presented at a peak level of 80dB SPL. A total number of 1024 sweeps were averaged using a 500-6000 Hz bandpass. The level of TEOAE was spectrally analyzed and automatically determined at different frequency bands.
Distortion Product Otoacoustic Emission (DPOAE) was recorded using the IHS two-channel evoked potential recording apparatus with Smart EP software, version 4.5 with smart OAE 4.5 software. Two tones were used: L1 = 65 dB (SPL) and L2 = 55 dB SPL, while f2/f1 was 1.22. Both the amplitude of the response of the distortion product (DP) at 2f1-f2 and background noise (Ns) were obtained at nine points corresponding to f2 frequencies of 553, 783, 1105, 1560, 2211, 3125, 4416, 6250, and 8837 Hz. These measurements were used to build a DP-gram by displaying the DP against the f2 frequency. The signal-to-noise ratio (SNR) was measured (SNR = DP – Ns) at each of these nine points. DPOAE was considered normal, reflecting normal cochlear function if the SNR was > 3 dB SPL on at least 70% of the tested frequencies.
Statistical analysis was performed using SPSS program version 16. Data are presented as means ± standard deviation (SD). Student's t-test, analysis of variance (ANOVA), and the Bonferroni post-hoc test were used for comparisons. The level of statistical significance was P ≤ 0.05.